It's a shortcut from a parking lot to the beach. It's not really visible on the photo but the path starts with a steep slope because the ground is lower than the parking lot -- if it were a planned path there would have been steps or something. Also it would almost certainly be paved.

For Sequence Sorter, use Insertion Sort. First rule of sorting: bubble sort is never the right answer :)

Exposure Mask Viewer is all about carefully managing the way your nodes communicate. Try first designing a program that draws lines with given location and width. Then use that program to draw rectangles.

Signal Window Filter is magic and I don't understand my own solution anymore...

Java applets and Javascript could interact with each other. I think it was called LiveConnect? Javascript could call Java methods, and Java applets could run Javascript code. It still works in current browsers I think, I actually needed to use it a couple of years ago.